The present invention relates to the delivery of a plurality of chemical components in well bore applications. More particularly, this invention relates to delivery capsules and methods of using such delivery capsules for facilitating the delivery of at least a plurality of chemical components to subterranean well bores.
Using delivery capsules is a well-known method of providing or facilitating the delivery of chemicals to perform a desired function. For instance, the use of ingestible gelatin capsules is a commonly used technique for the effective and safe delivery of pharmaceuticals and dietary supplements. In such applications, liquid preparations are typically encapsulated in gelatin capsules, while particulate or powdered preparations are typically encapsulated in two-part hard gelatin capsules. The capsules are designed to release their contents after ingestion, typically by a sort of degradation or dissolution of the capsule wall. Other common uses of delivery capsules include the delivery of cosmetic or paint ingredients.
Similar capsules, however, heretofore have not been available for use in subterranean well bore applications as a means to deliver or facilitate the delivery of chemical components to a well bore or the surrounding subterranean formation to perform a desired function, e.g., acidizing, foaming, or the like. Such capsules are beneficial in that they, inter alia, may aid in the handling of potentially hazardous chemical components. For instance, when a well bore is acidized, acid is generally pumped into the well from a tank and into the portion of the formation to be treated. The acid, while in transit before, during, and after the acidizing treatment, presents a potential hazard to the equipment and personnel exposed to the acid. Moreover, such acids can have the tendency to attack the pumps, the metal tubing leading to and within the casing as well as all necessary oil well tools and connecting lines. The expense of repairing or replacing the corrosion-damaged parts may be very high and undesirable.
Such capsules are also beneficial in that they may, inter alia, aid in the delivery of chemical components where it is desired that they combine and react downhole. For instance, when a well bore fluid such as a drilling fluid, spacer, or cement is pumped into the well and then foamed in situ. The capsulated components used to produce the foamed fluid are placed in the fluid that is pumped downhole and then released, whereby they react and foam the fluid located in the well. The reduced expense of conventional foaming equipment needed at the surface can be desirable.